Improved tumor localization of 111In labeled monoclonal antibody with chelator administration to host nude mice

Administration of calcium disodium edetate (EDTA) substantially increased the tumor:muscle ratios of nude mice injected with 111In labeled monoclonal antibody 9.2.27. This effect was apparent 3 days to 7 days after antibody injection of mice bearing the BRO human melanoma, but not earlier. The tumor:muscle ratios decreased during this time for animals not receiving chelator. Contemporaneously, EDTA treated mice lost whole body radioactivity more rapidly than did their untreated counterparts, suggesting that 111In which had dissociated from the antibody-DTPA-radiometal complex was chelated and excreted. These results suggest that effective chelator treatment might improve tumor localization of radioactivity after injection of 111In labeled antibodies.